Diagenetic K-feldspar pseudomorphs in the Triassic Buntsandstein sandstones of the Iberian Range, Spain     

SADOON MORAD  RAFAELA MARFIL  JOSÉ ANDRÉS DE LA  PE&#;A 《Sedimentology》1989,36(4):635-650

Early diagenetic K-feldspar in the Triassic Buntsandstein of the Iberian Range (Spain) occurs as pseudomorphs after detrital K-feldspar (Or<93) and plagioclase (Ab<96). These pseudomorphs are chemically pure (Or>99), untwinned, commonly heavily clouded by vacuoles and tiny inclusions, dark-luminescing and are composed of numerous fine euhedral crystals of K-feldspar. The latter property suggests that the pseudomorphs form via dissolution of detrital K-feldspar and plagioclase and precipitation of authigenic K-feldspar. X-ray diffraction analysis shows that the authigenic K-feldspar is intermediate microcline.  相似文献   

Digital Analysis of Shoreline Change     

P. R. O'REGAN  M. MORAD  A.I. CHALMERS 《New Zealand geographer》1995,51(2):25-31

This paper examines the potential of digital mapping techniques for the analysis and mapping of shoreline change. The discussion is illustrated through a case-study of the coastal environment of TePuru in the Coromandel Peninsula.  相似文献   

Peri-Urbanisation and Rural Roads     

ANTHONY ELSON  LEX CHALMERS  MUNRO MORAD 《New Zealand geographer》1996,52(2):65-69

This paper examines the impact of periurban development on the physical capacity of the roading network in an area to the north west of Tauranga, exploring the potential impact of subdivision, population growth and building of new residences in rural areas with respect to pressures on rural roads. Geographic Information Systems (GIS) are used to integrate large volumes of complex road and other data, model traffic flow generated from these data, display the outcomes effectively and test the effect of different development scenarios in a particular peri-urban environment.  相似文献   

Lessons for New Zealand from Britain's Foot and Mouth Epidemic     

MAIRI JAY  MUNIR MORAD  ANGELA BELL 《New Zealand geographer》2003,59(1):40-49

This paper explores some implications for New Zealand's rural community of Britain's foot and mouth epidemic in the light of growing international trade and travel, and changes in New Zealand's rural society. The paper includes ecological mapping with a projected/likely spatial distribution of an epidemic in New Zealand, and an assessment of the possible institutional and social responses in the wake of a disease outbreak. It notes the course of the epidemic in Britain, and possible differences and similarities in institutional response frameworks between Britain and New Zealand.  相似文献   

Diagenesis of a mixed siliciclastic/evaporitic sequence of the Middle Muschelkalk (Middle Triassic), the Catalan Coastal Range, NE Spain   总被引：1，自引：0，他引：1  

S. MORAD  I. S. AL-AASM†  F. J. LONGSTAFFE‡  R. MARFIL§  L. F. DE ROS  H. JOHANSEN¶  M. MARZO 《Sedimentology》1995,42(5):749-768

The Middle Muschelkalk (Middle Triassic) of the Catalan Coastal Range (north-east Spain) comprises sandstone, mudstone, anhydrite and minor carbonate layers. Interbedded sandstones and mudstones which are dominant in the north-eastern parts of the basin are terminal alluvial fan deposits. South-westward in the basin, the rocks become dominated by interbedded evaporites and mudstones deposited in sabkha/mudflat environments. The diagenetic and pore water evolution patterns of the Middle Muschelkalk suggest a strong facies control. During eodiagenesis, formation of microdolomite, anhydrite, baryte, magnesite, K-feldspar and mixed-layer chlorite/smectite was favoured within and adjacent to the sabkha/mudflat facies, whereas calcite, haematite, mixed-layer illite/smectite and quartz formed mainly in the alluvial facies. Low δ¹⁸O_SMOW values for microdolomite (+23.7 to +28.4%) and K-feldspar overgrowths (+17.3 to +17.7%) suggest either low-temperature, isotopic disequilibrium or precipitation from low-¹⁸O porewaters. Low-¹⁸O waters might have developed, at least in part, during low-temperature alteration of volcanic rock fragments. During mesodiagenesis, precipitation of quartz overgrowths and coarse dolomite occurred in the alluvial sandstones, whereas recrystallization of microdolomite was dominant in the sabkha/mudflat facies. The isotopic compositions of these mesogenetic phases reflect increasing temperature during burial. Upon uplift and erosion, telogenetic calcite and trace haematite precipitated in fractures and replaced dolomite. The isotopic composition of the calcite (δ¹⁸O_SMOW=+21.5 to +25.6%o; δ¹³C= 7.7 to - 5.6%o) and presence of haematite indicate infiltration of meteoric waters.  相似文献   

Diagenesis and formation water chemistry of Triassic reservoir sandstones from southern Tunisia   总被引：5，自引：0，他引：5  

S. MORAD  H. N. BEN ISMAIL†  L. F. DE  ROS  I. S. AL-AASM‡  N-E. SERRHINI† 《Sedimentology》1994,41(6):1253-1272

The fluvial Triassic reservoir subarkoses and arkoses (2409·5–2519·45 m) of the El Borma oilfield, southern Tunisia, were subjected to cementation by haematite, anatase, infiltrated clays, kaolinite and K-feldspar at shallow burial depths from meteoric waters. Subsequently, basinal brines controlled the diagenetic evolution of the sandstones and resulted initially in the precipitation of quartz overgrowths, magnesian siderite, minor ferroan magnesite and anhydrite. The enrichment of siderite in ¹²C isotope (δ¹³C_PDB= - 14·5 to - 9‰) results from derivation of carbon from the thermal decarboxylation of organic matter. During further burial, the precipitation of dickite and pervasive transformation of kaolinite into dickite occurred, followed by the formation of microcrystalline K-feldspar and quartz, chlorite and illite, prior to the emplacement of oil. Present day formation waters are Na-Ca-Cl brines evolved by the evaporation of seawater and water/mineral interaction and are in equilibrium with the deep burial (≤ 3·1 km) minerals. These waters are suggested to be derived from the underlying Silurian and Devonian dolomitic mudstones.  相似文献